Objective:To explore the influencing factors of psychological distress in breast cancer patients undergoing radiotherapy.Methods:A total of 177 breast cancer patients who were treated in Linyi Cancer Hospital from July 2017 to August 2020 were selected by the convenient sampling method. According to Distress Management (DM) Scale score, they were divided into no psychological distress group ( n=92) and psychological distress group ( n=85) . Binomial logistic regression analysis was used to explore the influencing factors of psychological distress in breast cancer patients. Results:The results of binomial logistic regression analysis showed that age, education level, monthly family income, payment method of medical expenses, complications and social support were the influencing factors of psychological distress ( P<0.05) . Conclusions:Breast cancer patients undergoing radiotherapy may experience psychological distress due to the influence of social support, age, monthly income, educational level and complications. Carrying out risk-based cancer care plans for these factors can improve psychological state and reduce psychological distress of patients.